Fuel metering apparatus and method

A method of supplying a quantity of fuel for combustion with the air ingested by an internal combustion engine of a vehicle and maintaining a scheduled mass ratio between the fuel and air both supplied in fluid form to the engine comprising the steps of:

• sensing a selected set of ambient parameters which affect the mass flow of at least one of said fluids and generating electrical signals each related to a different one of said sensed ambient fluid parameters,
• generating an electrical signal in response to at least one mode of engine operation and representative of a desired mass fuel-air ratio for that mode of operation of the engine,
• sensing the air supplied to the engine and generating a pulsatory electrical signal whose pulse repetition rate characteristic varies with the volumetric flow rate thereof,
• sensing the fuel supplied to the engine and generating a pulsatory electrical current signal having a pulse repetition rate characteristic which varies with the volumetric flow rate thereof,
• modifying a pulse characteristic of one of said pulsatory fluid flow signals in accordance with a function of said desired mass fuel-air ratio representative signal,
• additionally modifying a pulse characteristic of one of said pulsatory fluid flow signals in accordance with at least one ambient parameter related signal of said set of sensed ambient fluid parameters, and
• thereafter electrically combining said modified fluid flow signals for controlling the mass flow of fuel relative to the air into the engine in accordance with a predetermined relationship between said fluid flow signals that will maintain the actual mass flow of fuel supplied to the engine relative to the air ingested thereby in accordance with the desired mass fuel-air ratio signal.

In a closed loop regulated fluid metering system for supplying a quantity of a first fluid for combustion with a quantity of a second fluid ingested by an internal combustion engine and maintaining a scheduled mass ratio between the two fluids, said system comprising in combination,

• means for sensing a selected set of ambient parameters which affect the mass flow rate of at least one of said fluids,
• mass fluid ratio scheduling means responsive to several different modes of engine operation and providing a corresponding output signal representative of a desired mass ratio of said fluids for each different mode of engine operation,
• means for sensing one of the fluids supplied to the engine and generating a pulsatory electrical signal whose pulse repetition rate characteristic varies with the volumetric flow rate thereof,
• means for sensing the other of the fluids supplied to the engine and generating a pulsatory electrical signal whose pulse repetition rate characteristic varies with the volumetric flow rate thereof,
• means for modifying a pulse characteristic of one of said pulsatory fluid flow signals in accordance with a function of a desired mass fluid ratio representative signal from said mass fluid ratio scheduling means for a corresponding mode of engine operation,
• correction means for additionally modifying a pulse characteristic of one of said pulsatory fluid flow signals in accordance with at least one ambient parameter of said set of ambient parameters and
• control means responsive to and electrically combining said fluid flow signals as modified by said scheduled mass fluid ratio signal and by said correction means for controlling the mass flow of said first fluid relative to said second fluid into the engine in accordance with a predetermined relationship between said fluid flow signals that will maintain the actual mass flow of said first fluid supplied to the engine relative to the said second fluid ingested thereby in correspondence with the desired mass fluid ratio scheduled by said mass fluid ratio scheduling means for each different mode of engine operation.